Photographic image-receiving material



United States Patent 3,351,469 PHOTOGRAPHIC IMAGE-RECEIVING MATERIAL Louis Maria De Haes, Edegem, Belgium, assignor to Gevaert Photo-Producten N.V., Mortsel, Belgium, a company of Belgium No Drawing. Filed Apr. 6, 1966, Ser. No. 540,510 Claims priority, application Netherlands, Oct. 20, 1960, 257,057 4 Claims. (CI. 96-76) The present invention relates to an improved photographic material to be employed in the silver complex diffusion transfer process.

The present application is a continuation in part of the United States application Serial No. 359,455.

According to the known silver complex diffusion transfer processes, the operation of which is described in United States patent specification 2,352,014, in British specifications 614,155 and 654,630 and in German patent specification 887,733, a light-sensitive silver halide material is exposed to an image and then pressed into contact with a specially prepared receiving material in the presence of a developer and a silver halide solvent. In the exposed areas the silver halide is developed and does not undergo any further change. In the unexposed areas the silver halide is complexed by a complexing agent for silver halide which is present either in the developer or in the receiving material, whereupon the complexed silver halide is transferred by diffusion onto the receiving layer and converted therein by development into metallic silver. The conversion is effected by the catalytic action of the development nuclei present in the receiving or silver precipitating layer. These nuclei consist of finely divided metal or metal sulfide. In this way, an image is formed in the receiving layer, which image becomes visible after the separation of the image-receiving material'from the light-sensitive material.

' In order to obtain a uniform diffusion of the complexed silver halide, a temporary close contact of emulsion layer and receiving layer is necessary. If, however, both layers contain hardened or unha'rdened gelatin, the adhesion power is too strong on separation. Attempts have been made to avoid this difficulty by substituting other bindin g agents for the gelatin.

Thus it is knoWn, as shown in German patent specification 869,008 that the separation of emulsion and receiving layers is facilitated by wholly or partly replacing the gelatin in at least one of these layers with other layer-forming substances such as cellulose derivatives, polyamides, polyesters, polyvinyl alcohols, polyvinyl acetates, partially hydrolized polyvinyl acetates, polyvinyl acetals, or other synthetic or natural resins.

It is also known, as shown in British patent specification 748,892 to incorporate starch into the emulsion and image receiving layers.

It is further known, as shown in British patent specification 814,154 that the separation of emulsion and image-receiving layers can be effected even after practically complete drying if starch ether or galacto-mannan is incorporated into at leastone of these two layers.

Another method of facilitating the separation of the emulsion layer from the image-receiving layer consists in applying a thin auxiliary layer onto the emulsion layer and/or onto the image-receiving layer. It is known, as shown in the German patent specification 1,055,953 that starch or starch derivatives can be used for this purpose.

The layers manufactured according to the processes described in the above-mentioned patent literature can, however, be easily damaged during the squeezing of the emulsion layer and image-receiving layer between the rollers of the developing apparatus, so that poorly defined images are formed. This difiiculty is very often 3,351,469 Patented Nov. 7, 1967 experienced when the emulsion and imagereceiving layers are quickly separated from each other.

It has now been found that even when the emulsion and image'receiving layers are left in contact with each other for only a short time after the silver complex diffusion transfer, sharply defined images can be obtained if the image-receiving material comprises successively a support, a gelatin image-receiving layer containing development nuclei and an alginate surface layer, the former layer being hardened in situ by a hardening agent for gelatin present in the coating composition of the alginate layer, and the latter layer being insolubilised in situ by a suitable Water-soluble metal salt present in the coating composition of the image-receiving layer.

Any water-soluble metal salt which forms a water-insoluble compound with the alginate can be used. Suitable metal salts are the water-soluble salts of calcium, strontium, barium, cerium, uranium, titanium; chromium, manganese, iron, cobalt, nickel, copper, zinc, silver, cadmium, mercury, aluminium, thallium and lead. These water-soluble metal salts are incorporated into the coating composition of the image-receiving layer. The amounts of added metal salts may vary widely but are preferably chosen between 5 and 20 g. per litre of coating composition for the image-receiving layer.

The alginate used for coating. the surface layer is soluble in water. Its molecular weight may vary between 18,000 and 200,000. Suitable alginates for this purpose are e.g. sodium alginate, potassium alginate, ammonium alginate, magnesium alginate and triethanolamine alginate. They are used in aqueous solutions in concentrations which may vary between 5 and g. per litre of coating composition. These amounts, however, are not at all critical, and if it is convenient may be varied outside these limits.

For the hardening of the gelatin binder of the image according to the present invention. The said adhesion seems likewise to be improved very considerably by applying the alginate layer at a relatively high temperature, viz, between 60 and C.

An important advantage in the use of the image-receiving material according to this invention is the greater range of manipulation conferred to the silver salt diffusion transfer process. Indeed, due tothe short contact times of light-sensitive material and image-receiving material, the same light-sensitive material can successfully be used for the manufacture of a second, a third, etc., diffusion transfer print. Also for use in developing apparatus that operates at a developing speed of 7.5 cm./sec., the quick bath treatment can now be coupled with a quick separation of the light-sensitive and image receiving materials so that the diffusion transfer process is speeded up considerably. Moreover, due to the strongly improved mutual adhesive properties, the image-receiving material can be separated from the light-sensitive material after a long contact time and even after complete drying Without the risk of tearing these materials.

As to the use of this new process, it can be employed generally with the known processes of the silver complex diffusion transfer technique and the respective known materials such as are described in Process in Photography, vol. I, 1940-1950, pages 76-77 and vol. II, 1951- 1954, pages 156-7; vol. III, 1955-1958, pages 24-36 and in the patent literature cited therein.

Any silver halide emulsion can be used in the process of this invention, except only that its exposed silver salt is sufficiently rapidly developed during the diffusion transfer process and its non-exposed silver salt is sufficiently rapidly complexed. For this purpose, silver chloride emulsions, which may contain silver bromide or silver iodide, or to which other ingredients have been added, so as to impart the desired emulsion characteristics, are preferably used.

The image-receiving layer is a gelatin layer containing development nuclei. Development nuclei for complexed silver halides suitable for obtaining the silver-containing image in the image receiving layer are the sulphides of heavy metals such as, e.g., of antimony, bismuth, cadmium, cobalt, lead, nickel, silver and Zinc. Selenides, polysulfides, polyselenides, mercaptans, tin (II) halides, heavy metals or their salts and fogged silver halides are also suitable for this purpose. The complex salts of lead sulfide and zinc sulfide are effective either in themselves or mixed with thioacetamide, dithiobiuret and dithio-oxamide. Among the heavy metals, silver, gold, platinum, palladium and mercury are particularly worthy of mention, especially in their collodial form. The precious metals among them are the most active.

The composition of the developing solution for the silver halide is that of the conventional developing solution for the silver complex diffusion transfer: it contains the necessary ingredients for the development of the exposed silver halide such as hydroquinone and 1-phenyl-3-pyrazolidone and sometimes a solvent for the undeveloped silver halide, e.g., sodium thiosulphate, sodium thiocyanate or ammonia. The solvent for silver halide may, of course, be present in the image-receiving material as well as in the developer.

More particulars on the composition of the silver halide emulsion layer, the image-receiving material and the baths, and for the exposing and developing apparatus are given in the last cited literature and to the patent specifications mentioned therein.

The following examples illustrate the present invention without limiting, however, the scope thereof.

I Example 1 A 90 g./sq. m. paper support is coated with an imagereceiving layer from a 40 C. warm suspension of the following composition:

This suspension is cast in such a way that 1 1. thereof covers 40 sq. m. of paper. After drying, a second layer is applied from the following solution at 60 C.:

Ammonium alginate g 25 Water cm. 965 40% aqueous formaldehyde cm.

in such a way that with 1 1. thereof 50 sq. m. of paper are covered, whereafter this layer is dried.

The image-receiving material thus obtained is together with an image-wise exposed light-sensitive material, comprising a silver halide emulsion layer in the usual way conducted through a developing bath of the following composition:

terial have been pressed to each other by the rubber rollers of the developing apparatus, they are separated again from each other and a positive image of the original becomes visible in the receiving material.

Example 2 The same favorable results as in Example 1 can be attained when in the suspension of Example 1 the strontium chloride is replaced by calcium chloride.

Example 3 A g./sq. in. paper support is coated with a receiving layer as described in Example 1. After drying a second layer is applied thereon from the following solution at 60 C.:

Ammonium alginate g 60' Water cm. 930 40% aqueous formaldehyde cm. 10

in such a way that 1 litre thereof covers 50 sq. m. of paper, whereafter this layer is dried. The image-receiving material is conducted through a developing bath together with an image-wise exposed silver halide material such as described in Example 1. After leaving the squeezing rollers of the developing apparatus the image-receiving and light-sensitive materials are dried occasionally by means of heat and finally separated from each other, A positive image of the original is obtained in the receiving material.

I claim:

1. An image-receiving material for use in the silver complex diffusion transfer process comprising successively a support, a gelatin image-receiving layer containing development nuclei and an alginate surface layer, the former layer being hardened in situ by a hardening agent for gelatin present in the coating composition of the alginate layer, and the latter layer being insolubilised in situ by a suitable water-soluble metal salt present in the coating composition of the image-receiving layer.

2. An image-receiving material according to claim 1,

wherein the hardening agent for gelatin is formaldehyde.

3. An image-receiving material according to claim 1, wherein the water-soluble metal salt for the insolubilisation of the alginate surface layer is selected from the group consisting of water-soluble calcium and strontium salts.

4. An image-receiving material according to claim 1, wherein the alginate surface layer is applied at a temperature between 60 and 90 C.

References Cited UNITED STATES PATENTS 2,366,439 1/1945 Chilton et al. 9683 X 2,543,181 2/1951 Land 96--29 2,647,056 7/1953 Land 9629 2,835,576 5/1958 Ensink 9694 X NORMAN G. TORCHIN, Primary Examiner.

R. E. MARTIN, Assistant Examiner, 

1. AN IMAGE-RECEIVING MATERIAL FOR USE IN THE SILVER COMPLEX DIFFUSION TRANSFER PROCESS COMPRISING SUCCESSIVELY A SUPPORT, A GELATIN IMAGE-RECEIVING LAYER CONTAINING DEVELOPMENT NUCLEI AND AN ALGINATE SURFACE LAYER, THE FORMER LAYER BEING HARDENED IN SITU BY HARDENING AGENT FOR GELATIN PRESENT IN THE COATING COMPOSITION OF THE ALGINATE LAYER, AND THE LATTER LAYER BEING INSOLUBILISED IN SITU BY A SUITABLE WATER-SOLUBLE METAL SALT PRESENT IN THE COATING COMPOSITION OF THE IMAGE-RECEIVING LAYER. 